158 



SCIENCE. 



[Vol. XIV. No. 344 



a car and replace them by another set in from two to three minutes. 

 When the car enters this rack, its panels are dropped down on 

 either side and thus form bridges over which the batteries are 

 withdrawn from and replaced in the car. While this change is 

 being made, a competent person inspects the regulators of the car. 

 The motors, gearings, and connections are only inspected once a 

 day, and that at the end of the day's work. 



GOLD EXTRACTION BY A NEW PROCESS. 

 In many places where gold-bearing quartz is found containing 

 a sufficient percentage of the metal to pay for working it, there is 

 either an entire absence of the water necessary to work the process 

 at present employed for its extraction, or it can only be obtained 

 at great expense and trouble, in many cases only part of the year. 



which he could quickly determine whether any specimens of quartz 

 contained gold, by simply crushing it with a hammer and running 

 it through the machine. The mechanism of this apparatus con- 

 sists of an inclined ladder with fine wire cloth upon one side and 

 silk upon the other. A blast of air is passed up and down through 

 the two meshes, blowing off the light particles of dirt and quartz 

 and allowing the free gold to be retained simply by gravity. An- 

 other machine is adapted for concentrating various metals from 

 rock, such as sulphates of copper, lead, zinc, and antimony, making 

 the future separation of the valuable metals from the metallic 

 mass, by roasting or chemical processes, an easy matter. During 

 the exhibit an interesting experiment was made to show the value 

 of the machines, and the thoroughness with which they performed 

 their work. The machine used in the experiment weighed about 

 five hundred-weight, and was so compact that it could be readily 



FIG, 3. — STANDARD ELECTRIC CAR. JULIEN STORAGE BATTERY SYSTEM. 



Hitherto the processes used for extracting the gold from the allu- 

 vial deposit or from crushed quartz have required large quantities 

 of water to flush the fine, pulverized material containing the gold, 

 and even with the best methods large quantities of gold were car- 

 ried off with the earth and quartz and lost before it reached the 

 mercury. 



The need of some ready method for the dry extraction of the 

 gold has long been felt, but until recently the various machines 

 proposed have not been found equal to the old processes. The 

 various difficulties in the way of dry extraction have apparently 

 been overcome in a new machine which was exhibited in London 

 a few weeks ago. By this process, as described in Iron, the use 

 of mercury is dispensed with, and the gold is extracted readily from 

 alluvial deposits or quartz. The process is also applicable to the 

 extraction of any combination of metals from refractory ore. One 

 of the machines exhibited weighed but six pounds, and was in- 

 tended to form part of the outfit of the prospector, by the use of 



transported from one place to another. A quantity of gold ii> 

 minute particles, weighing six drams, and two small nuggets, 

 were put into a large pan with two hundred-weight of gravel and 

 grit, and the whole mass put into the machine, which was operated 

 with about a quarter-horse power, or, as an equivalent, two-man 

 power. 



The principle of the machine is similar to the small separator used 

 for prospecting purposes, with the blast of air driving off the fine 

 particles of extraneous material, while " oscillating riddles contain- 

 ing shot shake off the heavier grit and stones, allowing free gold 

 to sink by gravity into the shot, where it is retained, and in turn 

 falls to the bottom of the shot." In about a minute after the mix- 

 ture was placed in the machine the whole treatment was com- 

 pleted, and of the amount of gold originally put into the machine 

 96.3 per cent was recovered. With more time devoted to the 

 separation, a considerably smaller percentage of loss would doubt- 

 Isss have ensued. 



